What's up? I read a few scrolls down that you wanted the deadbolt function explained, so here it is. With my '85 535i, you can unlock the car from the driver-side-door, passenger-side-door, and the trunk. I can also lock the car from all these locations. The deadbolt feature applies to the trunk. You can actually lock your trunk(depending on what year- yours is an 87 or 88 right?) and leave it locked even if you unlock the car from the doors. To test it out, I would have the car unlocked, oh, make sure all your doors are closed(if the driver's door is unlocked your locks could go crazy into the lock-unlock cycle, which happenned to me). Anyway, put your key in the trunk, horizontally I would think, and turn it 90* towards clockwise so the right of the key is at 6 o'clock. Now, simply pull the key straight out. Your whole car should be locked now. Next, unlock your car from either door. Go back to the trunk, and push in the button, and your trunk should not release. It should be locked for good, until you unlock it with your key. If you don't know, to unlock it stick your key in vertically, and turn the key 180* counter-clockwise, and then back to the horizontal position. If you press in the button now your trunk should pop up. Hope I've helped, even though I'm sure I made this seem complicated.